Skip to main content

Only If Changed

Skip a task unless at least one of its dependencies reported a change.

Usage​

Call OnlyIfChanged() on a task to make it conditional on upstream changes. If every dependency completed with Changed: false, the task is skipped and the OnSkip hook fires with reason "no dependencies changed".

deploy := plan.TaskFunc("deploy-config",
    func(
        ctx context.Context,
        c *client.Client,
    ) (*orchestrator.Result, error) {
        resp, err := c.Node.FileDeploy(ctx, client.FileDeployOpts{
            Target:      "_any",
            ObjectName:  "app.conf",
            Path:        "/etc/app/app.conf",
            ContentType: "text/plain",
        })
        if err != nil {
            return nil, err
        }

        return &orchestrator.Result{
            JobID:   resp.Data.JobID,
            Changed: resp.Data.Changed,
            Data:    orchestrator.StructToMap(resp.Data),
        }, nil
    },
)

restart := plan.TaskFunc("restart-service",
    func(
        _ context.Context,
        _ *client.Client,
    ) (*orchestrator.Result, error) {
        fmt.Println("Restarting service...")
        return &orchestrator.Result{Changed: true}, nil
    },
)
restart.DependsOn(deploy)
restart.OnlyIfChanged()

In this example, restart-service only runs if the deploy step actually changed the file on disk. If the file was already up to date, the restart is skipped.

How It Works​

The orchestrator checks the Changed field of every dependency's Result. If at least one dependency has Changed: true, the task runs normally. If all dependencies have Changed: false, the task is skipped with status StatusSkipped.

This is equivalent to a When guard that checks dependency results, but provided as a convenience for the common "only act on changes" pattern.

Example​

See examples/sdk/orchestrator/features/only-if-changed.go for a complete working example.